Higher-order effects in the Coulomb dissociation of halo nuclei are investigated by comparing the first-order perturbation theory to the numerical resolution of a time-dependent Schrödinger equation. The calculations are performed for the breakup on a lead target of ${}^{11}\mathrm{Be}$ and ${}^8\mathrm{B}$. The populations of the different partial waves composing the ${}^{10}\mathrm{Be}$-neutron or ${}^7\mathrm{Be}$-proton continuum reveal that couplings in the continuum remain significant even at high impact parameters and high projectile-target relative velocities. Although the total breakup cross section is fairly well described by a first-order approximation, its partial-wave components reached by the first-order transitions are significantly depleted toward other partial waves after the closest approach. The information extracted by assuming the validity of the first-order approximation is affected by an energy distortion. Another distortion is caused by the presence of a resonance as exemplified by the $5/2^{+}$ resonance of ${}^{11}\mathrm{Be}$. Such effects may partly explain discrepancies between direct and indirect measurements of the astrophysical S factor of the ${}^7\mathrm{Be}(\text{p},\gamma ){}^8\mathrm{B}$ reaction at stellar energies.

• Received 17 January 2005

DOI:https://doi.org/10.1103/PhysRevC.71.044609